P1340

P1340 in the Ford definition is a Camshaft Position Sensor B circuit fault on bank 1 — most commonly seen on the 4.6L/5.4L 3V Triton and other Ford Modular V8s that use separate CMP sensors per bank or per cam (intake/exhaust on VCT-equipped 3V heads). The PCM expects to see a clean digital pulse train from the CMP correlated with the CKP signal; P1340 sets when those pulses are missing, noisy, or out of phase with the crank. Cheapest-first ladder: (1) Scope the CMP signal at the PCM connector — should be a clean 0-5 V square wave that correlates one-pulse-per-cam-revolution with the CKP pulses; missing pulses or noise spikes are the signature of a cracked sensor or a chewed reluctor. (2) Pull the sensor and inspect the tip — metallic debris stuck to the magnetic tip is the smoking gun for cam-phaser tooth wear on a 3V Triton (the phaser is wearing internally and shedding metal onto the CMP). (3) Ohm the CMP harness pin-to-pin from sensor to PCM — Ford specs sub-5-ohm continuity; corrosion at the CMP connector (which sits where it catches valve-cover oil weep) is a $40 fix vs. a $300 sensor. Critical caveat: don't replace the CMP sensor before reading keep-alive memory for cam phaser DTCs (P0012, P0014, P0022, P0024) — if those are present along with P1340, the real problem is the variable cam timing phasers themselves, not the sensor, and replacing only the sensor returns the customer 200 miles later for the same code plus a now-rattling top-end. Also check KAM for unauthorized tunes — VCT-disable tunes are common on 3V Tritons and can leave the PCM commanding cam-timing strategies the hardware doesn't follow, which sets P1340 as a secondary symptom.

Vehicle-specific patterns: 2004-2010 Ford F-150 / Expedition / Navigator with the 5.4L 3V Triton is the absolute canonical P1340 — the variable cam phasers wear internally, the timing-chain tensioners weaken, the phasers rattle on cold start, and the CMP sensor reads garbage data because the cam is no longer in sync with the crank; the proper fix is a full phaser + chain + tensioner + guide service ($1800-$2800 in labor alone). 2005-2010 Ford Mustang GT 4.6L 3V sees the same pattern with lower frequency since Mustangs typically have lower miles than work trucks. 2007-2014 Ford Edge / Lincoln MKX / Explorer with the 3.5L Duratec V6 throws P1340 from a similar cam-phaser wear pattern. 2011-2016 Ford F-150 5.0L Coyote sees P1340 occasionally from VCT solenoid screen clogging (gold-screen oil-filtration screen at the solenoid clogs with sludge on extended oil-change intervals); a $80 solenoid + screen clean clears it. Estimated repair: $180 (CMP sensor + harness pigtail) to $2,800 (full phaser/chain job on a 5.4L 3V Triton).